Portable tool for drilling holes in hardened steel

ABSTRACT

A portable tool for drilling holes in hard metal pieces, such as safe lock mounting plates, employing a high speed electric drill, a lever arm, a fulcrum at one end of the lever arm, means to adjustably attach the fulcrum to a support near the workpiece and means operatively connecting the lever arm at an intermediate position thereof to the drill body in such a manner that the force applied to the lever towards the workpiece is transmitted along the axis of the drill bit thus making it possible to drill a hole rapidly and with minimal effort and at various angular positions.

United States Patent 1191 OBrien 1 1 Jan. 8, 1974 PORTABLE TOOL FORDRILLING HOLES IN HARDENED STEEL [76] Inventor: Eugene OBrien, 5567Wheeler St.,

Philadelphia, Pa. 19143 [22] Filed: Mar. 9, 1972 [211 App]. No.: 233,059

[52] US. Cl 408/92, 408/712, 173/32 [51] Int. Cl. B23b 45/14 [58] Fieldof Search 408/92, 95, 712; 173/32 [56] References Cited UNITED STATESPATENTS 1,097,709 5/1914 Fosselman 408/92 1,763,552 6/1930 Cook 408/952,667,092 l/l954 Schaffer 408/92 3,122,032 2/1964 Schoonover 408/92 X2,768,663 10/1956 Jones 408/712 X 2,737,065 3/1956 Piersall 408/712 XFOREIGN PATENTS OR APPLICATIONS 1,260,440 3/1961 France 408/92 PrimaryExaminer-Andrew R. Juhasz Assistant Examiner-Z. R. Bilinsky Att0rneyMaxR. Millman [5 7] ABSTRACT A portable tool for drilling holes in hardmetal pieces, such as safe lock mounting plates, employing a high speedelectric drill, a lever arm, a fulcrum at one end of the lever arm,means to adjustably attach the fulcrum to a support near the workpieceand means operatively connecting the lever arm at an intermediateposition thereof to the drill body in such a manner that the forceapplied to the lever towards the workpiece is transmitted along the axisof the drill bit thus making it possible to drill a hole rapidly andwith minimal effort and at various angular positions.

9 Claims, 5 Drawing Figures PATENTED JAN 81974 SHEET 2 BF 2 i 1pm- FIG 51 PORTABLE TOOL FOR DRILLING HOLES I HARDENED STEEL This inventionrelates to a tool for drilling holes in resistant metals particularlyhardened steel.

The need to drill holes in hard metal plates and similar membersfrequently arises outside of a machine shop to which one cannottransport a drill press or use it effectively because it is too largeand cumbersome. One such application is the installation of a lock inthe mounting plate of a burglarized safe.

Heretofore, holes were drilled in case hardened steel using a high speeddrill and a carbide tipped twist drill bit. The procedure was tediousand uneconomical even using a high speed drill of about 5000 rpm sinceit took about three-quarters to one hour and a great deal of handpressure to drill a hole in one-fourth to threeeighth inch thickhardened steel. And, when one used a slower drill, at or below 2500 rpm,it would take several hours, if indeed it was able to accomplish thedrilling of a through hole at all. Frequently, one would end up merelywith a highly polished indentation and no more. Accordingly, locksmithshave frequently refused to repair burglarized safes for these reasons.

It is the primary object of this invention to provide a tool which willeffectively drill a hole in hardened metal using conventional carbidetipped twist drill bits which overcomes the disadvantages noted aboveand effects the drilling of holes in a fraction of the time, usuallyseconds, of that required in the method now in use thereby savingconsiderable time, effort and money.

Another object of the invention is to provide a tool of the characterdescribed which is portable and adjustable so that it can be readilytransported to sites requiring the drilling of holes in hardened metaland can reach areas generally considered inaccessible.

Another object is to provide a tool to drill holes in hardened metalwhich employs the mechanical advantages of a hand operated lever and ameans which causes the applied force to be transmitted axially of thedrill bit thereby making it possible for the rotating bit to force itsway through the workpiece quickly and with modest exertion, the holebeing thereby formed by a combination of abrasion and metal chippingcaused by heat generated due to friction between the bit and theworkpiece.

Another object of the invention is to provide a tool to drill holes inhardened metal in which the fulcrum of the hand lever can be adjustablyand removably secured to any accessible support and the tool can bereadily manipulated and operated in a variety of positions, horizontaland angular in addition to vertical.

Another object is to provide a tool of the character described which isrelatively simple in construction and design and hence relativelyinexpensive to manufacture and operate.

These and other objects of the invention will become more apparent asthe following description proceeds in conjunction with the accompanyingdrawings, wherein:

FIG. 1 is aside elevational view of the tool;

FIG. 2 is a sectional view taken on the line 2-2 of FIG. 1;

FIG. 3 is an elevational view looking to theleft on FIG. 1 of the tool;y

FIG. 4 is a sectional view taken on the line 4-4 of FIG. 3; and

FIG. 5 is a sectional view taken on the line 5--5 of FIG. 1.

Specific reference is now made to the drawings in which similarreference characters are used for corresponding elements throughout.

The tool is generally indicated at and employs a conventional electrichand drill 12, preferably a high speed drill, i.e. one which operates at2500-5000 rpm, and a carbide-tipped twist drill bit 14. The remainingcomponents comprise the means by which the conventional high speed drilland carbide-tipped twist drill bit may be transported to a work site andbe employedto rapidly and effectively drill a hole in a hardened metal,preferably case hardened steel, workpiece 16, such as a safe lockmounting plate. While the workpiece 16 is here shown lying horizontallyon a support 18 and the drill is generally vertical, it will beunderstood that this is merely illustrative since the tool can andprobably most often will be used in horizontal and angular positionswhere the location and disposition of the workpiece militates againstthe use of a drill in said vertical position.

An elongated lever member 20 is provided which comprises an outertubular member 22 of generally rectangular cross-section and a handle 24preferably a rod which is slidable through one open end 26 of thetubular member 22 and may be retained in a longitudinally adjustedposition therein by any suitable means as, for example, an elongatedslot 28 in one wall of the tubular member and a headed screw 30extending 1 therethrough and threadedly engaged in the handle 24 so thatthe head of the screw may be tightened against the slot in any adjustedposition.

The opposite end 32 of the tubular member 22 is also open and apredetermined length of its bottom wall is cut out to form an elongatedopening 34 as seen in FIG. 5. Intermediate its ends, the bottom wall ofthe tubular member is also cut out to form an opening 36 for a purposesoon to appear.

A pin preferably in the form ofa headed bolt 38 is provided whose shankextends transversely through the side walls 40 and 42 of the tubularmember 22 adjacent its end 32 and is there removably affixed by anappro* priate nut 44. The shank of the bolt 38 serves as a ful' crumupon which is pivotally mounted for movement around the axis of the boltone end of an adjustable anchor or tie member, preferably a length ofchain 46. The link 48 at one end of the chain is mounted over the shankof the bolt 38 and extends through the opening 34, the other end of thechain being equipped with an appropriate means, such as an eye member48, by which that end of the chain can be made to removably engage anappropriate support,.shown illustratively in FIG. 1 as a U-bolt 50.

Intermediate its ends, the lever member 20 is operatively connected to ameans by which the force exerted on the handle 24 towards the workpiecewill be effectively transmitted primarily along the axis 52 through thecasing or body 54 of the drill and the axis of the bit.

A rod 56 is provided whose upper end is flattened and extends throughthe opening 36 in the bottom of the tubular member 22 of the leverbetween its side walls 40 and 42 as seen in FIGS. 1 and 2. A headed bolt58 is provided whose shank extends through a transverse opening 60 inthe upper end of the rod 56 and through the side walls 40 and 42 andthere fixed by an 3 appropriate nut 61 so that the rod 56 is pivotalabout the axis of the bolt.

Another rod 62 is provided which has a reduced externally threadedportion 64 at its lower end and a reduced unthreaded portion 66 at itsupper end which contains a circumferential groove 68. The lower end ofthe rod 56 has an axial recess 70 opening therethrough which receivesthe reduced upper end portion 66 of the rod 62 and is retained for axialrotation therein by a set screw 72 carried by the rod 56 whose inner endextends into the groove 68.

A yoke member is provided which includes an upper bar 74 which spans thetop of the drill casing, a lower bar 76 which spans the bottom of thedrill and means holding said upper and lower bars against the drillcasing. The upper bar includes an arcuate cut-out 78 which receives andconforms to the upper curvature of the drill casing 54 opposite the bit.The lower bar includes a central stepped opening 80 to snugly receiveand seat the thrust collar 81 at the lower end of the drill casing todistribute the pressure thrust between bars 74 and 76, the drill chuck82 carrying the bit extending through said opening.

In the upper arcuate portion 84 of the drill casing, a recess 86 isprovided whose axis is in alignment with the drill bit axis 52. Theupper bar 74 of the yoke includes an internally threaded counterbore 88to receive the lower threaded reduced portion 64 of the rod 62. Openingthrough the upper bar 74 and communicating with the counterbore 88 is areduced internally threaded bore 90 which mounts an externally threadedset screw 92. Tie rods 94 interconnect the upper and lower bars and holdthem together tightly against the drill casing by appropriate lockingnuts 96.

In assembly, the electric hand drill casing 56 is placed in the yoke sothat the set screw 86 enters the center recess 86 in the upper arcuateportion 84 of the casing and the locking nuts 96 are tightened. Then theset screw 92 is tightened so as to hold the drill body and yoke firmlytogether and press the thrust collar 81 of the drill casing into thestepped recess 80 in the lower bar 76. It will be understood that thethrust collar 81 can be removably secured upon the bottom portion of thedrill casing by any suitable means as, for example, by the use ofa setscrew, screwing the thrust collar onto the casing itself, etc. The rodor post 62 is then screwed home into the counterbore 88' of the upperbar 74 to secure the set screw 92 from backing off. The upper rod 56 isplaced over the lower rod 62 and the set screw 72 is screwed in farenough to connect the rods 56 and 62 against separation but permitrelative axial movement between them. The lever is then mounted by meansof the bolt 58 on the upper rod 56 and the chain is mounted on one endof the lever by means of engagement of the bolt 38 in a selected one ofpairs of aligned holes 98 provided in the side walls 40 and 42 of thelever 22 to adjust the fulcrum. The handle 24 can then be extended tothe desired length by adjustment of the screw 30.

In use, the tool is transported to the site desired and the chain isattached in adjusted position to a suitable object such as an eyebolt,handle, hook or for that matter around an object, such as a small safe.The bit is held against the workpiece at any desired angle and whilelight pressure is exerted on the handle in a direction toward theworkpiece, the power to the drill is turned on. Pressure is increaseduntil the drill is cutting.

To drill a hole in case hardened steel, a high speed drill and a carbideor carbide-tipped twist drill is used and the action is such that assoon as the pressure is exerted the portion of the workpiece in contactwith the drill bit becomes cherry red and as the drill bit works its waythrough the metal workpiece red hot chips are removed. It was found thatwith the present tool a onequarter inch thick through hardened steelpiece having a Rockwell hardness of 48-50 was penetrated with aone-quarter inch diameter carbide-tipped twist drill bit using a highspeed drill, i.e. 2500-5000 rpm, in about four to about fifteen seconds.Depending upon the degree of hardness, drill speed and applied pressure,the time of penetration will vary but the tool will succeed in drillingthe hole in any event. Thus the tool penetrated a thick l 4sinchesdiam.) chrome through hardened ball bearing having a Rockwell hardnessof -65 in about one hour using a solid carbide bit.

The tool possesses the additional advantage in that it can be used todrill holes in hardened metal members at various angles and in generallyinaccessible places rapidly and efficiently and with a minimum ofeffort.

While a preferred embodiment of the invention has here been shown anddescribed, it will be understood that minor variations may be madewithout departing from the spirit of the invention and-the scope of theappended claims.

What is claimed is:

1. A portable tool for drilling holes in a metal workpiece comprising anelectric drill including a casing and a drill bit operatively carriedthereby, a lever arm, a fulcrum adjacent one end of the lever arm,adjustable tie means pivoted to said fulcrum and adapted to be attachedto a support in the vicinity of the metal workpiece, an elongated memberpivoted at one of its ends to said lever arm intermediate its ends aboutan axis transverse thereto, and means securing the other end of saidelongated member to said drill casing including a recess in the end ofsaid drill casing opposite said drill bit and in alignment with the axisof said drill bit, a yoke member, a pin carried by said yoke memberengaged in said casing recess, and means securing the other end of saidelongated member to said yoke member above and in alignment with saidrecess and behind said pin, said yoke member including a pair of barsengaging said drill casing at said bit end and the end of said drillcasing containing said recess, and tie members removably holding saidbars together against said drill casing.

2. The combination of claim 1 wherein said pin is a set screw.

3. The combination of claim 2 wherein said set screw ,is carried by andextends through the bar of said yoke member which engages the end ofsaid casing provided with said recess, a threaded counterbore in saidyoke member, said other end of said elongated member being threaded andreceived in said counterbore and bearing on said set screw.

4. The combination of claim 1 wherein said elongated member comprisestwo rod sections and means interconnecting them for axial movement ofone section relative to the other.

5. The combination of claim 4 wherein said means includes a reducedportion included in one rod section, a recess in the other rod sectionreceiving said reduced portion, a circumferential groove in said reducedportion and a set screw carried by the other rod section and engaged insaid groove.

6. The combination of claim 1 and means to adjust said fulcrum along thelength of said lever arm.

7. The combination of claim 1 wherein said adjustable tie means pivotedto said fulcrum is a chain.

8. A portable tool for drilling holes in a metal workpiece comprising anelectric drill including a casing and a drill bit operatively carriedthereby, a lever arm, a fulcrum adjacent one end of the lever arm,adjustable tie means pivoted to said fulcrum and adapted to be attachedto a support in the vicinity of the metal workpiece, and meansinterconnecting said lever arm intermediate its ends and said drillwhereby the major force exerted on the lever arm towards the workpieceis transmitted along the axis of said drill bit, said lastnamed meansincluding an elongated member pivoted at one of its ends to said leverarm about an axis transverse thereto, and means securing the other endof said elongated member to said drill casing so that the axis of saidelongated member is maintained in alignment with the axis of said drillbit, said elongated member comprising two rod sections one having areduced portion, a recess in the other rod section receiving saidreduced portion, a circumferential groove in said reducedportion and aset screw carried by the other rod section and engaged in said groove sothat the rod sections are removably connected for relative rotarymovement.

9. A portable tool for drilling holes in a metal workpiece comprising anelectric drill including a casing and a drill bit operatively carriedthereby, a lever arm, a fulcrum adjacent one end of the lever arm,adjustable tie means pivoted to said fulcrum and adapted to be attachedto a support in the vicinity of the metal workpiece, an elongated memberpivoted at one of its ends to said lever arm intermediate its ends aboutan axis transverse thereto, and means securing the other end of saidelongated member to said drill casing including a recess in the end ofsaid drill casing opposite said drill bit and in alignment with the axisof said drill bit, a yoke member, a pin carried by said yoke memberengaged in said casing recess, and means securing the other end of saidelongated member to said yoke member above and in alignment with saidrecess and behind said pin, said yoke member including a pair of bars,one engaging said drill casing at said bit end and the other engagingthe end of said drill casing containing said recess and means removablyholding said members together against said drill casing.

1. A portable tool for drilling holes in a metal workpiece comprising anelectric drill including a casing and a drill bit operatively carriedthereby, a lever arm, a fulcrum adjacent one end of the lever arm,adjustable tie means pivoted to said fulcrum and adapted to be attachedto a support in the vicinity of the metal workpiece, an elongated memberpivoted at one of its ends to said lever arm intermediate its ends aboutan axis transverse thereto, and means securing the other end of saidelongated member to said drill casing including a recess in the end ofsaid drill casing opposite said drill bit and in alignment with the axisof said drill bit, a yoke member, a pin carried by said yoke memberengaged in said casing recess, and means securing the other end of saidelongated member to said yoke member above and in alignment with saidrecess and behind said pin, said yoke member including a pair of barsengaging said drill casing at said bit end and the end of said drillcasing containing said recess, and tie members removably holding saidbars together against said drill casing.
 2. The combination of claim 1wherein said pin is a set screw.
 3. The combination of claim 2 whereinsaid set screw is carried by and extends through the bar of said yokemember which engages the end of said casing provided with said recess, athreaded counterbore in said yoke member, said other end of saidelongated member being threaded and received in said counterbore andbearing on said set screw.
 4. The combination of claim 1 wherein saidelongated member comprises two rod sections and means interconnectingthem for axial movement of one section relative to the other.
 5. Thecombination of claim 4 wherein said means includes a reduced portionincluded in one rod section, a recess in the other rod section receivingsaid reduced portion, a circumferential groove in said reduced portionand a set screw carried by the other rod section and engaged in saidgroove.
 6. The combination of claim 1 and means to adjust said fulcrumalong the length of said lever arm.
 7. The combination of claim 1wherein said adjustable tie means pivoted to said fulcrum is a chain. 8.A portable tool for drilling holes in a metal workpiece comprising anelectric drill including a casing and a drill bit operatively carriedthereby, a lever arm, a fulcrum adjacent one end of the lever arm,adjustable tie means pivoted to said fulcrum and adapted to be attachedto a support in the vicinity of the metal workpiece, and meansinterconnecting said lever arm intermediate its ends and said drillwhereby the major force exerted on the lever arm towards the workpieceis transmitted along the axis of said drill bit, said last-named meansincluding an elongated member pivoted at one of its ends to said leverarm about an axis transverse thereto, and means securing the other endof said elongated member to said drill casing so that the axis of saidelongated member is maintained in alignment with the axis of said drillbit, said elongated member comprising two rod sections one having areduced portion, a recess in the other rod section receiving saidreduced portion, a circumferential groove in said reduced portIon and aset screw carried by the other rod section and engaged in said groove sothat the rod sections are removably connected for relative rotarymovement.
 9. A portable tool for drilling holes in a metal workpiececomprising an electric drill including a casing and a drill bitoperatively carried thereby, a lever arm, a fulcrum adjacent one end ofthe lever arm, adjustable tie means pivoted to said fulcrum and adaptedto be attached to a support in the vicinity of the metal workpiece, anelongated member pivoted at one of its ends to said lever armintermediate its ends about an axis transverse thereto, and meanssecuring the other end of said elongated member to said drill casingincluding a recess in the end of said drill casing opposite said drillbit and in alignment with the axis of said drill bit, a yoke member, apin carried by said yoke member engaged in said casing recess, and meanssecuring the other end of said elongated member to said yoke memberabove and in alignment with said recess and behind said pin, said yokemember including a pair of bars, one engaging said drill casing at saidbit end and the other engaging the end of said drill casing containingsaid recess and means removably holding said members together againstsaid drill casing.